All fundamental biological processes, including development, immunity, and tumorigenesis, are related to the selective and differential expression of genes in different tissues and cell types. The formation of many malignant tumors has been shown to be associated with the production and/or expression or increased production and/or expression of certain specific cell surface signaling molecules. One of the goals of modern molecular medicine is to find ways to target drugs selectively to reduce or eliminate the drug's off target toxic effects. Delivering drugs to a specific target that is unique to or expressed at higher levels in diseased cells types using targeting moieties such as antibodies, peptides or aptamers has been investigated. Attaching these targeting moieties directly to the drug through linkers or to nanoparticles has also been investigated.
There remains a need for new extracellular-targeted drug conjugates (EDC) for the treatment of disease. The present disclosure meets this need. There also remains a need for methods and reagents to identify and evaluate protein-protein interactions between the Na,K-ATPase and cell signaling pathway proteins on the cell surface. The present disclosure also meets this need.